Racing was canceled on Tuesday because of strong winds, but conditions on Wednesday were better for the delicate 72-foot vessels, which sport hard wings instead of traditional sails and use foils to lift their dual hulls out of the water. The boats, with a crew of 11, can achieve breathtaking speeds of 44 knots (50 mph).

"New Zealand dominated matches between the two teams in the first week of the America's Cup finals on San Francisco Bay, then lost momentum over the weekend when a vastly improved Oracle won its second and third matches, raising hopes of a last-minute comeback. Oracle, which lost six of the first seven races in the series, became far more competitive after making changes to its twin-hulled AC72 and has [been] greatly improving its upwind tacking."

The America's Cup, founded in 1851, began as a challenge between a vessel affiliated with England's Royal Yacht Squadron and the schooner America. America won the race handily, and the U.S. defended the trophy for the next 132 years, until Australia II became the first-ever challenger to win the race. Since then, it's been won by New Zealand and a syndicate from landlocked Switzerland.

Update At 6:15 p.m. ET. Race 12 Postponed Until Thursday:

KQED reports that the second race scheduled for Wednesday has been postponed because the wind had picked up beyond the 20-knot limit, "so they're done for the day."